19. Activated sludge Is formed by.
a.
Diffused air aerators.
b.
Primary settling.
c.
Mechanical aerators.
d.
Adding activated bacteria to digested sludge.
20. The stable products formed by biochemical wastewater treatment processes
are removed by ________________ ___________________, an essential part of
secondary treatment.
21. Approximately ____________ percent of the sludge from primary sedimentation
units is putrescible organic solids.
22. Under optimum conditions, well-digested sludge is produced in approximated
___________ days.
23. What products are formed In a sludge digester?
a.
Scum.
b.
Oxygen.
c.
Sludge gas.
d.
Schmutzdecke.
e.
Zoogeal film.
f.
Stable sludge.
g.
Activated sludge.
h.
Supernatant liquor.
MD0161
2-60